It has become relatively commonplace for portable devices, such as cellular phones, personal digital assistants (PDAs), laptop computers and the like, to supply power to certain external accessories, such as speakers, earphones, pointing devices and the like. The external accessories can present short-circuit conditions when attached to the portable device. In the portable devices, accidental short-circuiting of an external power supply output is a problem. Without short-circuit protection, if a power supply output is accidentally shorted to ground, the output voltage decreases and the output current increases significantly. The increased output current caused by the short circuit may damage the power sourcing device and its internal components.
Short-circuit protection circuits for portable devices are known. However, known short-circuit protection circuits are not completely adequate because they may not be able to terminate some short-circuit conditions quickly enough to prevent damage to the portable power sourcing device. Thus, there is a need for an improved short-circuit protection circuit that is suitable for use with portable devices.